AME infinite encoding

Hi, I've a problem with AME on my new MBP, I'm trying to encode a mkv file into mp4 to reduce dimension, but it takes infinite time. And generally everything seems to be very slow, like adding a new file to encode, AME freezes for a couple of minutes to add the file and this never happened with my old 2010 MBP!!

The file I'm working on it's 1920x1080 at 25fps and my specs are:

i7 3,3 GHz with 16 GB ram

with an integrated GPU Intel Iris Graphics 550

I've Sierra and CC 2017 Upgraded at the last update.